Ultrasound guided central neuraxial block

Abstract

Central neuraxial blocks (CNB) are the preferred blocks in the practice of regional anesthesia. Palpation
of the anatomical landmarks is used for the identification of the space, which is not always the best
method when CNB is performed in overweight patients or patients having atypical spines like scoliosis.
Ultrasound (US) has recently been utilized to facilitate CNB. However, CNB US can be difficult, because
the structures need to be visualized by US are surrounded by bones, which do not allow ultrasound rays
to pass through. Therefore in order to allow deeper penetration, the ultrasound probe used for CNB is
a curved probe of low frequency of 2-5 mHz, as it allows deeper penetration at the expense of image
resolution. There are two scanning planes; transverse and longitudinal which supplements each other.
US for CNB helps in determining the intercristal line, exact intervertebral level, midline, ideal point of
insertion, distance to ligamentum flavum and needle trajectory. US for CNB has improved patient safety
by decreasing the number of attempts, chances of dural puncture and damage to conus medullaris. It has
also improved patient satisfaction and has proved to be an ideal learning tool for the trainees.